Watson and Crick proposed that DNA is made of ____________ chains that ____________ around each other in the shape of a __________________, a shape similar to a winding spiral staircase.

(a)  

Part of the work of Watson and Crick was ____________ diffraction ____________ of __________________.

(a)  

The photographs and crystals were produced by researchers __________________ and __________________, at King's college in England.

(a)  

In 1962, ____________, ____________, and ____________ received the Nobel Prize in ____________ for their work on ____________.

(a)  

(a)   died in 1958 and so could not be named in the Nobel Prize.

Each nucleotide consists of thre parts:

The five-carbon sugar in a DNA nucleotide is called (a)   .

The alternating ____________ and ____________ molecules form the side "____________" of the staircase.

(a)  

Nucleotides along each strand are connected by __________________ between the ____________ of one nucleotide and the __________________ of the next nucleotide.

(a)  

Each full turn of the DNA helix has a (a)   nucleotide pairs.

The bases on one strand of DNA face and form bonds called (a)   with the bases on the other strand.

In each pair one base has a ____________ structure and the other base has a ____________ structure.

(a)  

__________________ between the ____________ help hold the two chains of the DNA double helix together.

(a)  

Base pairing rules:

A = ___ (___ hydrogen bonds in between)

C = ___ (___ hydrogen bonds)

(a)  

Nitrogenous bases that have a ____________ ring of ____________ and ____________ atoms, such as adenine and guanine, are called ____________.

(a)  

Nitrogenous bases that have a ____________ ring of ____________ and ____________ atoms, such as cytosine and thymine, are called ____________.

(a)  

The order of nitrogenous bases on a chain of DNA is called its (a)   .

"Mistakes" or changes in the sequence of DNA are called ____________. ____________ can be ____________, ____________ or have ____________.

(a)  

Base pairing rules - in DNA, ____________ on one strand pairs with ____________ on the opposite strand, and ____________ pairs with ____________.

(a)  

The base-pairing rules help create the (a)   structure of DNA.

DNA replication is the process by which ____________ is copied in a cell before a cell divides by ____________, ____________, or __________________, during ____________ of ____________.

(a)  

In step 1 of DNA replication, enzymes called ____________ separate the DNA strands. They move along the DNA molecule, breaking the __________________ between the complementary __________________. The Y-shaped region that results when the two strands separate is called a __________________

(a)  

In step 2 of DNA replication, Enzymes called __________________ add complementary nucleotides, found floating freely inside the ____________, to each of the ____________ strands.

(a)  

In step 3 of DNA replication, the result is ____________ ____________ and ____________ DNA molecules that are ready to move to new cells in __________________.

(a)  

In each new DNA __________________, one strand is from the ____________ molecule, and one strand is ____________. This type of replication is called __________________ replication beacause each of the new DNA molecules has kept (or conserved) one of the ____________ (or semi) original DNA strands.

(a)  

In prokaryotic cells, which have one circular chromosome, replication begins at one place along the chromosome. ____________ replication forks are formed and proceed in ____________ directions, like two ____________ opening in ____________ directions.

(a)  

In prokaryotic cells, replication continues along each fork until they ____________ and the entire molecule is ____________.

(a)  

Eukaryotic cells have (a)   replication forks.

(a)   have repair functions that "proofread" DNA.

Chemicals and ultraviolet radiation from the sun can ____________ ____________.

(a)